Most conventional internal combustion engines, such as those used on motorized vehicles, including automobiles and boats, use a mixture of fuel and air for combustion. The fuel can comprise gasoline, diesel fuel, or compressed gas such as propane. This mixture is drawn into the engine through a carburetor by a negative pressure created during intake strokes of engine operation. Alternately, a carburetor is not used but the fuel is injected by mechanical or electronic means directly into the combustion chambers or the intake manifold. In either case the fuel and air mixture is compressed and ignited, with the combustion generating power at the output shaft of the engine.
The amount of fuel and air necessary to secure proper combustion will vary according to the type of fuel used, altitude, speed, load, temperature and design of the engine. The carburetor is used to control the mixture of air and fuel to the engine.
The air flow through the carburetor is commonly controlled by a pivoted valve, commonly a butterfly-type valve located between the carburetor and the fuel intake manifold. A user typically directs the throttle valve into an open position by depressing a gas pedal, or moving a throttle lever. The opening of the valve allows more air to flow into the engine, with the negative pressure from the intake stroke of the pistons causing the air to flow through the carburetor. The increased air flow uses a venturi effect to draw fuel out of openings disposed within the air flow. The greater the air flow velocity, the more fuel that is drawn into the stream of air.
U.S. Pat. No. 4,872,440 to Green is of this general type. Green describes rotating rings which adjust the amount of air flow, with the air flow in turn affecting the amount of vacuum that draws fuel into a mixing chamber and then into the engine. Similarly, Fabritz U.S. Pat. No. 4,058,102 describes a reciprocal plate which varies the air flow which in turn affects the atomization of fuel used by an engine. In both the Green and Fabritz patents, the air flow aperture is varied, and the amount of fuel is indirectly varied according to the air flow passing through the air flow valve.
In other carburetors, fuel flow is controlled, while air flow is indirectly varied. The patent to Kendig, U.S. Pat. No. 4,482,507, describes a fuel dispersion bar extending across a flow passage below two generally rectangular valve gates. The dispersion bar has fuel flow slits which are simultaneously opened, closed, or partially opened by longitudinally moving a shaft. The shaft movement is controlled by the fuel pressure through a diaphragm in a fuel pressure control assembly. The amount of fuel flow is indirectly affected by the opening of the valve gates through the fuel pressure diaphragm, and through the longitudinal movement of the shaft which varies the fuel aperture.
The metering systems of Kendig, as well as other metering systems used in the prior art are disadvantageous because of the resulting complexity of the carburetor. The indirect link between the throttle valve, the air valve, and fuel dispersion system requires a large number of components making the carburetor not only more expensive, but more susceptible to breakdown and failure. There is thus a need for a simple carburetor providing desirable control over the air to fuel mixture.
The prior art carburetors have a number of adjustment capabilities, which when combined with the indirect affect air flow has on fuel flow, results in a carburetor which is difficult to adjust for optimum performance. There is thus a further need for a carburetor which permits the synchronous adjustment of airflow and fuel flow without the need of numerous and complex components.
When the carburetor metering systems of the prior art are adjusted for optimum performance at a particular altitude, the carburetor maintains that predetermined setting regardless of the altitude. At higher altitudes, the size of the air opening in the carburetor may be the same, but the amount of air flowing through the opening is reduced because of the reduced air density at higher altitudes. Thus the engine performance is reduced as the altitude varies. This is a constant problem for motorists living near mountains, or those who travel across the country. There is thus a need for a carburetor which accommodates for the effects of differential altitude.
It is therefor an object of the present invention to provide a relatively simple carburetor whereby the air flow and fuel flow are directly controlled, rather than being indirectly controlled and connected.
It is a further object of the present invention to provide a new mechanism and method of dispersing the fuel into the air stream through the carburetor.
It is a further object of the present invention to provide a carburetor design which accommodates for the adverse effects which altitude variations may have upon engine performance.
It is a further object of the present invention to provide a carburetor which provides a simple adjustment and variation of the carburetor's performance.